The DFT Theoretical Study on Properties of Surfactant at Gas and Liquid Interface
Hydrations of dimethyldodecylamine-N-oxide and sodium dodecyl sulfonate are fully optimized calculation at 298 K and 1.013 ×105 Pa with Gaussian 03 program.Calculations are carried out at the B3LYP/6-31G*level using density functional theory.Interaction between surfactant and water molecules(number of water molecules n=1～3)is studied.And the formation,stability and influencing factors of the interface are also analyzed.The results clearly show that Hydrogen-bonded complexes of surfactant are stabile and a significant negative charge transfers from surfactant to water.Hydration of surfactant is spontaneous process.Gibbs energies of surfactant hydrate is re-duced.On the basis of this DFT calculation,the charges distribution of hydration are also studied.And theoretical study on interaction and arrangement of surfactant at gas and liquid interface has been carried out.The results show that the hydrophobic part near to hydrophilic groups have like charges as the hydrophilic group,while the end of hy-drophobic group far from the hydrophilic group has a partial negative charge.Surfactants can form a stable and ordered arrangement through hydrogen bonding and electrostatic forces in the gas and liquid interface layer.Further-more,there is a strong positive and negative electrostatic force between the molecules of dodecyl dimethylamine oxide and sodium dodecyl sulfonate hydrate,which has a synergistic effect and improves interface stability.
surfactanthydrationdensity functional theory(DFT)gas and liquid interface
万方数据
维普
